Diverse ink jetting processes have been developed for the recording method by means of an ink-jet printer, and any process comprises generating ink droplets to deposit onto various recording materials (such as paper, film, cloth) for recording. The recording method by means of ink-jet printer has rapidly been spread in recent years and will be propagated in future because the method brings about no mechanical noise due to the system in which a recording head does not contact with the recording material and because the method advantageously allows the printer to become downsized, to work in a high-speed and to give color printing, easily. For recording an image information or a character information pictured on a computer color display in color by means of an ink-jet printer, the information is generally printed according to subtractive color mixing of inks of four colors, namely yellow(Y), magenta(M), cyan(C) and black(K). In order to print reproducibly an image pictured by additive color mixing of red (R), green (G) and blue (B) on a CRT display as faithfully as possible according to subtractive color mixing, the dyestuffs to use, especially ones for a Y, M or C ink, are desired to have color hues close to the respective standards of Y, M and C and vividness. Additionally, it is required that the resulting ink composition is stable for long-term storage and that the resulting printed image is of a high optical density and has excellent fastness including water fastness, light fastness, gas fastness and so on.
Ink-jet printers are increasingly used in a wide range from a small one for OA use to a big one for industrial use. So, excellence in fastness such as water fastness and light fastness of the printed image is more strictly demanded. The water fastness is substantially improved by coating inorganic micro particles such as porous silica, a cationic polymer, alumina sol or special ceramics which can absorb dyestuff from ink, on a paper sheet together with PVA resin. Further improvement in quality such as moisture fastness is desired in order to store the printed matter such as photos in good condition. However, light fastness is not yet improved by any established technique. Among tetrachromatic colors of Y, M, C and K, magenta especially has many dyestuffs which are naturally weak in light fastness, and the improvement is an important problem to be solved.
The typical types in chemical structure of magenta dyestuffs used in a water-soluble ink for ink-jet recording are a xanthene type and an azo type using the H acid. The xanthene type is indeed excellent in hue and vividness, but is very inferior in light fastness. The azo type using the H acid is good in hue and water fastness, but is inferior in light fastness and vividness. Some magenta dyestuffs in this type being excellent in vividness and light fastness have been developed, but are still inferior in light fastness to dyestuffs of the other hue such as yellow dyestuffs and cyan dyestuffs represented by copper phthalocyanine type.
Recently, the digital camera having been in widespread use, the chance to print out photos at home is increasing. However, there is a problem of color change in photos during storage by the oxidizing gas in the air.
Alternatively, for a chemical structure of magenta dyes being excellent in vividness and light fastness, an anthrapyridone type is known (for example, refer to patent literatures 1 to 8), but can not yet show any satisfactory properties in hue, vividness, light fastness, water fastness, gas fastness and dissolving stability.    Patent literature 1: JP Laid-Open No. 74173/1984 (1 to 3 pages),    Patent literature 2: JP Laid-Open No. 16171/1990 (1 and 5 to 7 pages),    Patent literature 3: JP Laid-Open No. 109464/2000 (1 to 2 and 8 to 12 pages),    Patent literature 4: JP Laid-Open No. 169776/2000 (1 to 2 and 6 to 9 pages),    Patent literature 5: JP Laid-Open No. 191660/2000 (1 to 3 and 11 to 14 pages),    Patent literature 6: JP Laid-Open No. 72884/2001 (1 to 2 and 8 to 11 pages),    Patent literature 7: JP Laid-Open No. 139836/2001 (1 to 2 and 7 to 12 pages)    Patent literature 8: JP Laid-Open No. 192930/2003 (1 to 4 and 11 pages)